A method and structure for reducing the corrosion of the copper seed layer during the fabrication process of a semiconductor structure. Before the structure (or the wafer containing the structure) exits the vacuum environment of the sputter tool, the structure is warmed up to a temperature above the water condensation temperature of the environment outside the sputter tool. As a result, water vapor would not condense on the structure when the structure exits the sputter tool, and therefore, corrosion of the seed layer by the water vapor is prevented. Alternatively, a protective layer resistant to water vapor can be formed on top of the seed layer before the structure exits the sputter tool environment. In yet another alternative embodiment, the seed layer can comprises a copper alloy (such as with aluminum) which grows a protective layer resistant to water vapor upon exposure to water vapor.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for forming a seed layer on a semiconductor structure, the method comprising the steps of: depositing the seed layer on the semiconductor structure in a tool, the seed layer comprising a metal; bringing the seed layer to a process temperature above a water condensation temperature of an ambient environment surrounding the tool while the semiconductor structure and the seed layer remain in the tool, wherein the seed layer has not been subjected to water vapor prior to said bringing the seed layer to the process temperature; and then transferring the semiconductor structure and the seed layer out of the tool resulting in the seed layer being exposed to the ambient environment surrounding the tool while a temperature of the seed layer is above the water condensation temperature.
2. The method of claim 1 , further comprising the step of, after said transferring is performed, depositing a bulk layer directly on the seed layer, wherein the bulk layer comprises the metal.
3. The method of claim 1 , wherein the metal comprises a material selected from the group consisting of copper and a copper alloy.
4. The method of claim 1 , wherein the step of depositing the seed layer on the semiconductor structure comprises the steps of: depositing a diffusion barrier layer on the structure, the diffusion barrier being capable of preventing diffusion of the metal; and depositing the seed layer on the diffusion barrier layer.
5. The method of claim 1 , wherein said bringing the seed layer to the process temperature comprises the step of flowing a gas into direct physical contact with the seed layer.
6. The method of claim 5 , wherein the gas comprises a gas inert to materials of the structure.
7. The method of claim 5 , wherein the step of flowing the gas into direct physical contact with the seed layer is performed in a chamber in the tool.
8. The method of claim 1 , wherein said bringing the seed layer to the process temperature is performed in a cool station in the tool.
9. The method of claim 1 , wherein said bringing the seed layer to the process temperature comprises the step of placing the structure including the seed layer on a chuck being at a temperature not below the process temperature.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
May 13, 2004
June 26, 2007
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